MIAMI (CBSMiami) — A Miami-Dade firefighter has been arrested for sharing what investigators say were x-rated pictures of underage girls on Twitter.

Gabriel Diaz was arrested late Thursday on 16 counts of promoting sexual performance by a child.

According to our news partners, the Miami Herald, Diaz allegedly shared 16 images of underage girls having sex on the social media website.

The investigation into Diaz became public in December 2013 when he was reassigned to desk duty after police raided his home and seized his computers. Officials also seized his work computer.

His lawyer said in December, the longtime firefighter had done nothing wrong. He was just sharing adult content with his friends on Twitter using the name “ot_a_ku2”, not knowing they could possibly contain girls between the ages of 14 and 17.

In Diaz’s case, Twitter initially flagged several questionable photos and sent them to The National Center for Missing and Exploited Children. Investigators there analyzed the photos and confirmed that at least seven portrayed “child victims’ who had been previously identified by law enforcement. Of those, only two of the images showed what could be considered “sexual conduct” under Florida law, police concluded in a search warrant.

But since then, sexual crimes detectives combed through thousands of images on his Twitter account and found at least 16 that were confirmed to be of underage girls.

Diaz worked in the Public Education Unit at the department where he gave fire safety and medical emergency presentations to school children.

Late Friday, The Miami-Dade Fire Rescue Department issued this statement:

“Firefighter Gabriel Diaz is on paid administrative leave from Miami-Dade Fire Department pending the outcome of the investigation. He has been with Miami-Dade Fire Rescue for 17 years.”